The Gene Targeting and Transgenic facility was founded over 20 years ago to assist AECC researchers in the generation of genetically modified mouse models of human disease. Until recently, the Gene Targeting and Transgenic components operated as independent Shared Resources, each being rated outstanding at the last CCSG review. Following relocation to new state-of-the-art laboratory space in the Price Center, the facilities were merged into one Gene Targeting and Transgenic Shared Resource. The Transgenic component of the facility continues to generate, with high efficiency (-100% success rate), transgenic mouse strains through the introduction of DNA sequences, such as regular plasmid vectors or BAC clones into the germ line by pronuclear injection or by lentivirus infection of fertilized oocytes. For each project, the facility supervisor consults with individual investigators and advises on transgene construct design, as well as making plasmids and sequence cassettes available to ensure suitable for expression in the mouse. Typically 20-25 investigators use this service with approximately 100 constructs injected per year. The Gene Targeting component continues to provide services for modification of the mouse genome through the use of gene targeting methods in embryonic stem (ES) cells and introduction of these changes into the mouse germline. Gene Targeting services include the generation of conventional knockout mouse lines, knock-in mouse lines and mouse lines with conditional alleles for the temporal and spatial ablation of genes. The facility has a high success rate (>95%) for obtaining gene targeted mouse. Finally, a new Gene Modification Service was implemented by the Albert Einstein College of Medicine to provide a complete service for the rapid and cost efficient generation of genetically modified mouse lines to all AECC investigators. Services include the design and generation of simple and complex gene targeting vectors, electroporation and screening of embryonic stem cell lines of various genetic backgrounds (129, B6 and 129/06) and the generation of chimeric mice by blastocyst injection (performed by the Gene Targeting facility). The Gene Modification Service has also developed new technologies and procedures for high-throughput generation of targeting vectors and screening procedures and began full operation in early 2012.